This is a Phase I, randomized, placebo-controlled trial to determine the safety and immunogenicity of canarypox cytomegalovirus (CMV) vaccine. The study population consists of healthy, 18-35 year old adults. Volunteers were screened for antibodies to CMV, human immunodeficiency virus, and hepatitis B and C, as well as for hematologic and biochemical status. Once the results of the screening tests were known, volunteers were stratified into two groups, based on their CMV neutralizing antibody titers. Group 1 consisted of individuals who did not have neutralizing antibodies to CMV, while Group 2 consisted of individuals with neutralizing antibody titers of greater than or equal to 128. Subjects received immunizations of canarypox vaccine or placebo at months 0, 1, 3 and 6. Subjects were seen monthly for the first 7 months after the first immunization and then at months 12 and 26. During each study visit, an interim history was obtained and blood was drawn for hematologic, biochemical and immunologic studies. Subjects were required to maintain diaries that included a list of systemic reactions from days 0 to 7 and local reactions at day 3 after each dose.